Решение

class Solution {
    fun romanToInt(s: String): Int {
        var total = 0
        var prev = 0
        var i = s.length - 1
        while (i >= 0) {
            val v = when (s[i]) {
                'I' -> 1
                'V' -> 5
                'X' -> 10
                'L' -> 50
                'C' -> 100
                'D' -> 500
                else -> 1000
            }
            total += if (v < prev) -v else v
            prev = v
            i--
        }
        return total
    }
}